Modern farming conditions pose serious pressure on reaching the highest production performance potential of animals. In this stressful situation, feed contamination, an immature gut flora in young animals and a high stocking density can suppress the ability of the animal to maintain a healthy status and high production performance. Organic acids are known to be effective in improving feed hygiene and as such can support intestinal health. An integrated approach of organic acids combined with other types of feed additives provides four steering mechanisms for preserving feed materials and supporting intestinal health in farm animals in order to cope with the challenges and to achieve optimal production performance.

Prevent bacterial intake

A first important steering mechanism is the prevention of bacterial intake. Acidifiers such as organic acids reduce diet pH, creating unfavourable conditions for microbial growth in feed and drinking water. This lowers microbial counts in feed and water and in turn reduces uptake of microbes by the animals. It is known that a combination of organic acids applied in feed or drinking water provides a synergistic effect on a broad spectrum microbial level. Formic acid is an attractive acidifier with the lowest minimum inhibitory concentration (MIC) against a list of Gram negative and Gram positive bacteria in comparison with other organic acids. Test results on feed and water samples collected over several years in the Selko Laboratory have revealed that formic and acetic acid are very effective in reducing Salmonella and E. coli. Sorbic and benzoic acid show the same efficacy, but these acids are only available as dry products which are less easy dissolved in an acid blend. Propionic acid is less effective against E. coli and Salmonella, however, it has the highest efficacy against moulds. In vitro trial results have shown that a synergistic mixture of formic and acetic acid is most effective in inhibiting growth of E. coli and Salmonella both at the low concentration of 0.5kg/ton and at 1.5kg/ton (Figure 1). Despite the reduced microbial count in feed and water, after addition of organic acids some microbes will survive and be ingested by the animal. Naturally, in monogastrics the stomach pH is low, in order to impair survival of these ingested microbes. During intake of feed the pH in the stomach will rise, providing more favourable conditions for microbial growth. Organic acids will reduce stomach pH in the presence of feed, thereby supporting the natural barrier against bacteria. Moreover, proteolytic enzymes are activated at a low pH value and will improve digestion.

Microbiota management

A second important mechanism to optimise performance and health is proper management of the microbiota. Density and diversity of the intestinal microbial population increases from the upper towards the lower intestinal tract. The upper part of the small intestine of pigs and poultry is dominated by gram-positive bacteria (Richards et al 2005). The cell wall of gram-positive bacteria has a thicker peptidoglycan layer in comparison with Gram negative bacteria which makes this type of bacteria more acid tolerant. Medium chain fatty acids (MCFA) are able to destabilise the peptidoglycan layer of Gram positive bacteria, making it permeable for organic acid molecules to enter. Moreover, MCFA reduce respiratory capacity of bacterial cells resulting in reduced proliferation and cell death (Kabala and Marshall, 2005). Skrivanova et al (2006) showed with an MIC test, that from the tested range of fatty acids C2 – C18, lauric (C12) and myristic acid (C14) have the highest activity against Clostridium Perfringens. Laboratory test results showed that a synergistic blend of organic acids and MCFA has the highest log reduction capacity of both Gram positive and Gram negative bacteria compared to organic acids or MCFA alone (Figure 2). Furthermore, it has the lowest impact on the favourable Lactobacilli. Therefore MCFA are combined with organic acids in order to expand the spectrum of activity and support maintenance of a healthy microbial balance. MCFA are digested and absorbed in the upper intestinal tract of monogastrics. However, as we know that the density and diversity of microbiota increases further down the intestine, also in the lower intestine microbial balance support is important. Esterified fatty acids are broken down in the lower part of the small intestine. This results in available fatty acids in this part of the gut, which can optimise the microbiota balance in the lower gut.

Scientists from the Siberian Scientific Research Institute of Agriculture in Tomsk (Agricultural Center) have developed a feed additive that can help prevent iodine deficiency in cattle, reported the press-service of the Agrarian center of Tomsk Oblast.

"We are talking about developing a biologically active humic feed additive, which include macro and micronutrients. The additive is intended for cattle, sheep and goats in different age and physiological periods for prevention, improving productivity and eliminating iodine deficiency "- stated the press service of the Agricultural Center.

Studies have shown that the introduction of humic acids in the diet of animals can lead to an increase in milk production and fat content in cow's milk. Humic acids improve feed efficiency and decrease its costs. Humic feed additives are a rich in various vitamins, macro-and micronutrients that are vital to the growth and development of animals.

"But the problem of iodine deficiency in animals remains. Currently we are looking at developing a method for producing a feed additive from peat for the prevention and treatment of iodine deficiency in polygastric animals as well as to increase the profitability of milk production"- said in a statement of Agricultural Center.